From 01d6e2c16bf18d289b61a71da5ff23f39ff900bd Mon Sep 17 00:00:00 2001
From: Cheeserolls <dan@fullgun.com>
Date: Thu, 18 Jun 2015 00:20:11 +0100
Subject: [PATCH] Re-write potion init code to avoid clashes with other mods

---
 .../biomesoplenty/common/core/BOPPotions.java | 85 ++++++++++++-------
 1 file changed, 53 insertions(+), 32 deletions(-)

diff --git a/src/main/java/biomesoplenty/common/core/BOPPotions.java b/src/main/java/biomesoplenty/common/core/BOPPotions.java
index 96cdc7b07..bd7b84bf8 100644
--- a/src/main/java/biomesoplenty/common/core/BOPPotions.java
+++ b/src/main/java/biomesoplenty/common/core/BOPPotions.java
@@ -1,49 +1,70 @@
 package biomesoplenty.common.core;
 
-import static biomesoplenty.api.content.BOPCPotions.*;
+import static biomesoplenty.api.content.BOPCPotions.paralysis;
+import static biomesoplenty.api.content.BOPCPotions.possession;
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 
 import net.minecraft.potion.Potion;
-
-import org.apache.logging.log4j.Level;
-
-import biomesoplenty.common.helpers.BOPReflectionHelper;
 import biomesoplenty.common.potions.PotionParalysis;
 import biomesoplenty.common.potions.PotionPossession;
-import cpw.mods.fml.common.FMLCommonHandler;
+import cpw.mods.fml.common.ObfuscationReflectionHelper;
+import cpw.mods.fml.relauncher.ReflectionHelper;
+
 
 public class BOPPotions 
 {
-	public static int potionOffset;
-	private static final int MAXNEWPOTIONS = 8;
-
+	
 	public static void init()
 	{
-		extendPotionsArray();
-		intializePotions();
-	}
-	
-	private static void extendPotionsArray()
-	{
-		FMLCommonHandler.instance().getFMLLogger().log(Level.INFO, "[BiomesOPlenty] Extending Potions Array.");
-		potionOffset = Potion.potionTypes.length;
-		
-		Potion[] potionTypes = new Potion[potionOffset + MAXNEWPOTIONS];
-		System.arraycopy(Potion.potionTypes, 0, potionTypes, 0, potionOffset);
-
-		BOPReflectionHelper.setPrivateFinalValue(Potion.class, null, potionTypes, "potionTypes", "field_76425_a");
+		paralysis = new PotionParalysis(getSparePotionId(), true, 16767262).setPotionName("potion.paralysis");
+		possession = new PotionPossession(getSparePotionId(), true, 1280).setPotionName("potion.possession");
 	}
 
-	private static void intializePotions()
-	{
-		paralysis = new PotionParalysis(getNextID(), true, 16767262).setPotionName("potion.paralysis");
-		possession = new PotionPossession(getNextID(), true, 1280).setPotionName("potion.possession");
-	}
-	
-	public static int getNextID()
-	{
-		return potionOffset++ - 1;
-	}
+    
+    // gets the next free potion id
+    // will expand the potions array if necessary
+    public static int getSparePotionId()
+    {
+        // look for a free slot in the Potions array
+        // (note we start counting from 1 - vanilla MC doens't use ID 0, nor will we)
+        int n = Potion.potionTypes.length;
+        for (int i = 1; i < n; i++)
+        {
+            if (Potion.potionTypes[i] == null)
+            {
+                return i;
+            }
+        }
+        
+        // if there isn't a free slot, we'll expand the array...
+        
+        // things go wrong if you try and have more than 128 potions
+        if (n >= 128)
+        {
+            throw new RuntimeException("There are not enough spare potion IDs - Biomes O Plenty cannot create potions - you might have to remove some mods");
+        }
+        
+        // create a new potionTypes array - one bigger than the previous, and copy the old potions into it
+        Potion[] expandedPotionTypes = new Potion[n + 1];
+        System.arraycopy(Potion.potionTypes, 0, expandedPotionTypes, 0, n);
+        
+        // use reflection to replace Potion.potionTypes with our new expanded array
+        // note - need to specify both the obfuscated and de-obfuscated field names so that it works in dev and in the normal game        
+        Field field = ReflectionHelper.findField(Potion.class, ObfuscationReflectionHelper.remapFieldNames(Potion.class.getName(), "potionTypes", "field_76425_a"));
+        try
+        {
+            Field modifiersField = Field.class.getDeclaredField("modifiers");
+            modifiersField.setAccessible(true);
+            modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
+            field.set(null, expandedPotionTypes);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+
+        return n;
+
+    }
+ 
 }